The present invention relates to a liquid cooling system and an electronic equipment, and more particularly, to a liquid cooling system fixable to an outside of a housing of an electronic equipment and an electronic equipment using the same.
Semiconductor devices such as CPUs, etc. used in an electronic equipment such as a computer, etc. generate heat in operation, and such generated heat is further increased because high integration of semiconductors advances especially in recent years. Since semiconductors constituting CPUs, etc. lose the function as semiconductors when exceeding a certain temperature, it is necessary to cool semiconductor devices, which generate a large quantity of heat. For cooling semiconductor devices in an electronic equipment, there are known cooling methods with thermal conduction, with air cooling, with a heat pipe, and with liquid cooling.
In the cooling method utilizing thermal conduction, material having a large thermal conductivity is used for a radiation path extending from semiconductor devices to an outside of an electronic equipment. This method is suited for electronic equipment, in which the heat generated from the semiconductor devices is relatively small in quantity and which is compact like a notebook-sized personal computer.
In the cooling method utilizing air cooling, a blowing device such as a fan is provided within the electronic equipment so as to forcedly cool the semiconductor devices by convection. This method is widely used for cooling of semiconductor devices which generate a certain quantity of heat, and is also applied to a personal computer by making the blowing device small in size and thin.
The cooling method utilizing a heat pipe is made to be more efficient than the cooling method utilizing thermal conduction, and refrigerant encapsulated in the pipe transfers heat outside of the electronic equipment, which is known as described in JP-A-64-84699 and JP-A-2-244748. This method needs no use of parts which consume electric power, like a blowing device, and can perform efficient cooling.
In addition to the above cooling techniques, there is used a liquid cooling system for transferring heat with a cooling liquid. The concrete method with liquid cooling is known as described in, for example, JP-A-10-213370. In this method, a radiator, a pump, and a heat receiving jacket are arranged such that the heat receiving jacket is connected to the radiator and the pump by a suitable pipeline. The cooling liquid is transported to the heat receiving jacket by the pump so as to absorb heat from the heat generating body, and the heated cooling liquid is transported to the radiator to be cooled. That is, the pump circulates the cooling liquid so as to continuously transfer the heat received by the heat receiving jacket to the radiator and radiate it. Owing to the use of the cooling liquid, this method can perform more efficient cooling and is suited to cooling of semiconductor devices, which generate a large quantity of heat.
ln a cooling system utilizing the liquid cooling method, a cooling subject is liquid for heat transfer such as water, a nonfreezing fluid containing glycol, etc. Thus, it is necessary to provide a construction which prevents leakage of the cooling liquid at the time of maintenance or the like. As a conventional technique with respect to such cooling system taking account of leakage of the cooling liquid, there is known a technique described in, for example, JP-A-6-97338. With this conventional technique, an electronic equipment comprises at least two housings, that is, an electronic equipment housing, which accommodates therein heat generating semiconductor parts being cooled by the cooling liquid, and a cooling-liquid cooling housing, which accommodates therein cooling-liquid cooling means to cool the cooling liquid, cooling-liquid supply means to supply the cooled cooling liquid to the heat generating semiconductor parts, and the like, and the respective housings and pipes are connected together so that a whole electronic equipment can be handled as an integral structure. This conventional technique is suited to cooling of semiconductor devices, which generate a large quantity of heat, and is excellent in maintenance.
The conventional technique described in JP-A-64-84699 and JP-A-2-244748 has a limit in transferable quantity of heat and involves a problem that sufficient cooling cannot be achieved in cooling semiconductor devices, such as CPU, etc., which generate a large quantity of heat.
Also, with the conventional technique described in JP-A-10-213370, the liquid cooling system is stored in the housing of the electronic equipment, so that exchange of the pump, the radiator, etc. must be made at the time of maintenance or the like without cooling-liquid spilling into the housing. Methods for such exchange include two methods, that is, one for exchange of a liquid cooling system as a whole, and other for exchange each element, for example, a radiator, a pump, and the like. With the former method, there is caused a problem that the liquid cooling system is clamped over an entire area of the housing and so man-hour equivalent to that for disassembly of the apparatus is needed. Also, with the latter method, there is caused a problem that exchange must be made after drying subsequent to discharge of the cooling liquid, or made in a manner to prevent leakage of the cooling liquid, which requires complex man-hour.
Further, the conventional technique described in the above JP-A-6-97338 involves a problem that it is necessary to make the electronic equipment housing an exclusive one with a view to utilization of the liquid cooling system and to determine the liquid cooling system in view of a direction, in which the electronic equipment is installed. The reason for this is that since the liquid cooling system is constructed to unite with a tank for a cooling liquid, a distance between the liquid surface and inlet and exhaust ports of the tank cannot be made sufficient when orientation of the housing is changed, whereby air is mixed in the cooling liquid to cut off flow of the liquid, and the cooling capacity is lost, in particular, in case of a small-sized pump.